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CONTACT LENS I

CONTACT LENS I. Introductory course which will pertain to contact lens optics, preliminary evaluation, GP materials, fitting, patient education and problem-solving and soft lens materials, fitting, patient education and problem-solving. Comprehensive outlines, C/D and video will be provided.

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CONTACT LENS I

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  1. CONTACT LENS I • Introductory course which will pertain to contact lens optics, preliminary evaluation, GP materials, fitting, patient education and problem-solving and soft lens materials, fitting, patient education and problem-solving. • Comprehensive outlines, C/D and video will be provided

  2. COURSE GRADE • Two examinations and one final • First two examinations will be approximately 80% objective; 20% problem set • Minus and plus grades will be used; scale = 90 - 100 (A/A-); 80 - 89 (B- to B+); 70 - 79 =( C+ to C-): <70 = F • Two problem sets will be provided

  3. COURSE GRADE • Final Examination = 30% • First Examination 20% • Second Examination = 20% • Laboratory = 20% • Problem Sets = 10%

  4. COURSE OBJECTIVES • To guide you through the understanding of clinical optics as it pertains to rigid and soft contact lens design and fitting • To be prepared to determine who are good candidates & which contact lens material would be optimum for any given patient. • To exhibit decision-making capabilities in spherical rigid and soft contact lens material selection, design, care and problem-solving.

  5. TEXTS • Mandatory: Bennett/Henry: Clinical Manual of Contact Lenses (third edition); Lippincott-Williams & Wilkins, (available, November, 2008) • Recommended: • Hom: Manual of CL Fitting and Prescribing (2nd ed.) 2000 • Bennett/Weissman: Clinical Contact Lens Practice (2nd ed.) Lippincott/ Williams & Wilkins, 2005. • Bennett/Hom: Manual of Gas Permeable Contact Lenses (2nd ed.) Elsevier, 2004.

  6. RESOURCES • C/D: GP lens design, fitting and problem-solving • GP Clinical Management Guide • GP Benefits/Fitting/problem-Solving Laminated Card • GP Case Grand Rounds Troubleshooting Guide

  7. CLASS COMPETITION • Divided in to four groups • At designated lectures, cases will be presented. E-instruction will be used (clickers required) • Winning group visits Alcon (space available)

  8. RESEARCH PAPER • CL II research paper is due in mid- April; however, the topic will need to be approved by Dr. Bennett or Henry by early November (if project; otherwise by March 1) information is attached)

  9. COURSE OUTLINE • 8/20/08: Course Outline & Contact Lens History • 8/27/08: Contact Lens Optics

  10. COURSE OUTLINE • 9/03/08: Preliminary Evaluation Part One: Tear Film and Corneal Topography* • 9/10/08: Preliminary Evaluation Part Two: Patient Selection* • 9/17/08: EXAMINATION ONE

  11. COURSE OUTLINE • 9/24/08: GP Patient and Material Selection* • 10/01/08 & 10/08/08: GP Lens Design, Fitting & Evaluation* • 10/15/08: GP Care and Patient Education* • 10/22/08: NO Class (Academy Meeting)

  12. COURSE OUTLINE • 10/29/08: GP Problem-Solving • 11/05/08: Contact Lens Examination Two • 11/12/08: Hydrogel Lens Materials & Fitting • 11/19/08: Hydrogel Lens Care • 12/03/08: Hydrogel Lens Problem-Solving

  13. CONTACT LENS HISTORICAL DEVELOPMENTS

  14. INITIAL CONCEPTS • Leonardo Da Vinci: first person to neutralize the cornea by substituting a new refracting surface. About 1508, he described several forms of CLs to accomplish this. • Rene Descartes: first to suggest placing a CL directly upon cornea with scleral lens (about 1636 or 1637); demonstrated cornea’s role in astigmatism with hydrodiascope-like device

  15. BLOWN GLASS - FLUID • FA Muller (1887): Weisbaden glassblower made first nonoptical scleral lens • Fick (1888): Zurich physician: made first refractive-powered lens; large and designed for irregular corneas; blown glass • August Muller (1889): made lenses to correct his myopia; molded human eyes and made bicurve/tricurve designs; first to explain lacrimal exchange

  16. WEISBADEN LENS

  17. FLUIDLESS GLASS SCLERAL • Josef Dallos (Budapest): fluidless glass scleral lenses (large) using eye molds; corneal section optics; more secure, controllable and comfortable fit • Fenestrations minimized adhesion and enhanced lacrimal exchange

  18. FLUIDLESS GLASS SCLERAL • Adolf Mueller-Welt (Stuttgart, Germany): produced fluidless glass scleral lenses, beginning in 1927. • He designed lenses to allow lacrimal fluid to circulate between lens and cornea • First to develop large trial sets & inventories & (with Joe Breger), initiated one of the first CL labs in the U.S.

  19. MUELLER-WELT

  20. SCLERAL PMMA • PMMA served as the primary CL material from the late 1930’s to the late 1970’s due to: • Lower specific gravity • Better & faster reproducibility • Thinner • Could be fenestrated • Difficult to break

  21. SCLERAL PMMA • Feinbloom (1937): combined glass corneal section with a plastic section contact lens • First All PMMA Lenses (1938 - 1940): via numerous manufacturers • Still taking molds • Obrig Lab • Role of Sol Braff

  22. FEINBLOOM

  23. CORNEAL PMMA • Kevin Tuohy: California optician given credit for first corneal PMMA lens • Large: 11.5 - 12.5mm • Fitted flat • Thick with blunt edges • Patent granted in 1950

  24. CORNEAL PMMA • Butterfield (1950): modified Tuohy design for alignment fit • Design Changes: a change occurred from large, flat designs to small steep designs. Bayshore (1960) introduced a small diameter (7.0 - 8.6mm) steep design with a central fenestration to reduce edema • Fenestrations (1950’s-70’s) were used to reduce edema (3 central or 20 peripheral)

  25. CORNEAL PMMA • Major Laboratories: • Obrig (New York) • Breger-Mueller-Welt (Chicago) • Plastic CL Company (Wesley-Jessen, Chicago) • Had most influence on CL use increasing • In mid 1950s, they had 85% of CL market

  26. CORNEAL PMMA • Modified PMMA Designs (late 1950’s) • Vent Air: semicircular grooves in the posterior surface • Spiro Vent: “jet propulsion” posterior grooves designed to ensure rotation and tear flow • Stimson keraform lens: 4 projections to minimize rotation

  27. HYDROGEL LENSES • Historical Development • Wichterle • Hornstein • National Patent Development Corporation • Morrison • Isen

  28. HISTORICAL DEVELOPMENT • In 1963 and 1964, Dr. Otto Wichterle, Czechoslovakian polymer chemist developed a hydrophilic plastic compound (hydroxyethylmethacrylate or HEMA) • A child’s erector set was used to develop a spin-casting technique for shaping HEMA into contact lenses

  29. HISTORICAL DEVELOPMENT • Hornstein: first American to have access to Dr. Wichterle • Obtained some of Wichterle’s samples and technical information • Bypassed opportunity for further involvement (BM1)

  30. HISTORICAL DEVELOPMENT • National Patent Development Corporation: Martin Pollak (NPDC attorney) visited Dr. Wichterle in Prague (1964) • Applications were discussed and Dr. Bob Morrison was selected to assist • NPDC established Flexible CL Company • October, 1966 B & L signed a licensing agreement with NPDC (WJ: BM2) • FDA classified soft lens as drug; delayed product launch until 1971

  31. HISTORICAL DEVELOPMENTS • Robert Morrison: Rochet (French OD) told him of Wichterle; he visited Prague 10 times and brought back materials • First American to fit soft lenses • Czechs almost signed over patents until Pollak called • Signed “napkin” agreement with Pollak • Gave up 50% control of Flexible CL Co.

  32. HISTORICAL DEVELOPMENTS • Alan Isen: reported on hydrogels at 1964 American Academy of Optometry meeting • Became head of NPDC’s soft lens division (instead of Morrison)

  33. RIGID GAS PERMEABLE/Gas Permeable or GP Modified PMMA Designs (1970’s) • Ultrathin, low wetting angle • Cellulose Acetate Butyrate 1978 became the first approved RGP; very low O2 permeability and unstable • Silicone/acrylate (Polycon I): approved January, 1979; Gaylord patent of 1974; Seidner - Syntex - Sola-Barnes-Hind - Sola - WJ - Ciba • Fluoro-Silicone/acrylate: Boston Equalens (1986)

  34. SILICONE ELASTOMER • Becker (1956) developed silicone elastomer; advantages = O2 and flexibility; disadvantages = wettability & adherence • Breger worked on it from 1959 - 1972 • Dow Corning introduced it in the 1970s (Silsoft); sold it in 1984 • B & L has been working with it for almost 20 years (PureVision); Ciba sued (Focus Night and Day) = No PureVision

  35. OTHER DEVELOPMENTS • Extended Wear (1979); first 30 day aphakic and then myopic; high water thick lenses • Soft Torics: approximately 1980; initial lenses (WJ) were fine except for discomfort, poor vision and edema • Disposable Lenses: 1987 (Acuvue from Vistakon) • Opaque tints (late 1980s) (WJ) • Silicone-Hydrogel: 1998 (Bausch & Lomb Purevision)

  36. CARE SYSTEMS • GP: little change from PMMA except consolidation of wetting and soaking; use of liquid enzyme • Soft: Started with liquid heat units and then dry heat units (good disinfection; short lens life); in late 70s chemical disinfection was introduced (borderline disinfection; preservative Rxs & GPC); H2O2 in mid 1980s; effective chemical disinfection (ReNu/Optifree) in late 1980s

  37. CONTACT LENSES ISSUES AND CONTROVERSIES

  38. Contact Lenses as Commodity? Picture courtesy of EE/Class of 2005

  39. ISSUES AND CONTROVERSIES

  40. WHY CONTACT LENSES?

  41. WHY CONTACT LENSES

  42. THREE POINT TOUCH

  43. EVALUATION: FLUORESCEIN PATTERNS • Alignment: light, even pooling of fluorescein; slightly denser peripheral pooling due to flatter peripheral curve radius

  44. PIGGYBACK: TRADITIONAL

  45. Reverse Zone Optic Zone Alignment Zone Peripheral Zone

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